Dataset: Time-resolved fluorescence lifetimes of Dissolved Organic Matter in surface waters in the Upper Newport Back Bay estuary in California from May 2021 to July 2022

Upper Newport Back Bay near-shore surface waters at inlet, mid-estuary and outlet. Site 1 (33.650327, -117.8671967), located at the San Diego creek inlet; site 2 (33.6302266, -117.8859726), located mid-estuary; and site 3 (33.6181867, -117.9051099), located near the Newport Beach marina and Pacific Ocean outlet. 

Surface water (<5 cm) was sampled in the morning from the shore, stored in amber glass bottles, transported to the laboratory, filtered through 0.2 micron Durapore filters and stored in the fridge.  

Fluorescence lifetimes were measured using a Horiba DeltaFlex Lifetime System. The DeltaFlex system is a modular Time Correlated Single Photon Counting (TCSPC) system consisting of a high repetition rate LED source, a DD-C picosecond diode controller, a PPD picosecond photodetection module with DDS-1 power supply, and a DH-HT high throughput TCSPC controller.  The timing electronics has almost no counting photon loss and 10 ns dead times (Horiba Inc). Measurements were made with three different pulsed LED sources (DeltaDiode DD-260, DD-280, DD-340) with peak wavelengths of 268 nm, 285 nm and 338 nm and average power of 5 µW, 10 µW, and 2 µW, respectively. The bandwidth and maximum repetition rate for all LED sources was ~ ± 10 nm and 20 MHz respectively.  An instrument response function (IRF) was measured using a LUDOX AS-40 inorganic scattering suspension (Sigma Aldrich) solution.  

This is a summary of methods from De Bruyn et al., 2025 (see related publications).